package com.jielihaofeng.atguigu.nio;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * @author Johnnie Wind
 * @description 分散读写测试 Scattering：将数据写入到 buffer 时，可以采用 buffer 数组，依次写入 [分散] Gathering：从 buffer 读取数据时，可以采用 buffer 数组，依次读
 * @date 2021/11/25 14:18
 */
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws Exception {

        // 使用 ServerSocketChannel 和 SocketChannel
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);
        // 绑定端口并启动
        serverSocketChannel.socket().bind(inetSocketAddress);
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);

        // 等待客户端连接
        SocketChannel socketChannel = serverSocketChannel.accept();
        // 从客户端接收8个字节
        int messageLength = 8;
        // 循环读取
        while (true) {
            int byteRead = 0;
            while (byteRead < messageLength) {
                long l = socketChannel.read(byteBuffers);
                // 累计读取的字节数
                byteRead += l;
                System.out.println("byteRead=" + byteRead);

                // 使用流打印，看看当前这个buffer的position和limit
                Arrays.asList(byteBuffers).stream()
                        .map(buffer -> "position=" + buffer.position() + ", limit=" + buffer.limit())
                        .forEach(System.out::println);

            }

            // 将所有的buffer进行flip
            Arrays.asList(byteBuffers).forEach(buffer -> buffer.flip());

            // 将数据读出显示到客户端
            long byteWrite = 0;
            while (byteWrite < messageLength) {
                long l = socketChannel.write(byteBuffers);
                byteWrite += l;
            }

            // 将所有buffer进行clear
            Arrays.asList(byteBuffers).forEach(buffer -> buffer.clear());

            System.out.println("byteRead=" + byteRead + " byteWrite=" + byteWrite + ", messageLength=" + messageLength);
        }
    }
}
